1. Technical Field
The present invention relates to a radically polymerizable photo-curable ink jet ink composition.
2. Related Art
Ink jet recording ink compositions containing a white pigment are known. For example, JP-A-2007-99833 discloses a white ink jet ink composition mainly containing a white pigment, a polymer dispersant, a photo-curable compound, and a photopolymerization initiator for enhancing the dispersion stability of the ink composition to minimize the settling of the pigment in order to prevent the ink from clogging nozzles. In this ink, the polymer dispersant has a sulfonate group.
However, in the known ink compositions containing a white pigment, viscous sediment is deposited during long-time storage even if the ink composition contains a dispersant. The deposited sediment is difficult to redisperse sufficiently even by agitating the ink composition. The known white pigment-containing ink compositions are inferior in redispersing sediment deposited during long-time storage to restore it to a former dispersion, that is, inferior in redispersibility after long-time storage.